/Engine/Plugins/FX/Niagara/Source/NiagaraEditor/Public/Widgets/SItemSelector.h
An optional delegate to compare two categories for equality which must be supplied when generating categories for items. This equality comparer will be used to collate items into matching categories.
WidgetArgsType & OnCompareCategoriesForEquality &40; const FOnCompareCategoriesForEquality & InDelegate &41;